Floating car shows off cold side of highway mirages

You'd be forgiven for thinking this photo had been taking at the height of a baking hot summer's day, the usual time of year for spotting a mirage. But it is February on this road near Saskatoon, Saskatchewan, Canada. The temperature is -23 °C and yes, that's snow on the right hand side.

Mirages on roads are a familiar sight in hot weather, but at sub-zero temperatures, they are much harder to come by. However, it is essentially the same process that takes place.

The black asphalt of the road surface has been heated just a few degrees above the ambient temperature and as a result, a thin layer of air above the road surface warms up. The layer of warm air has a lower refraction index than the denser, colder air above it. The difference between them creates a boundary which behaves as a mirror, reflecting distant objects, in this case the blue winter sky, which makes it looks as if the car is floating above the road's surface.